Photographic developer



Sept. 9, 1941.

G. P. HAM ETAL 2,255,731

PHOTOGRAPHIC DEVELOPER Filed March l5, 1940 2 Sheets-Sheet l CONTROLFIG. l.-

INVENT OR. Garnef Philip Ham uswr'l a l3 4 5 s 7 a 9 W556i 57E/P5ATTORNEY.

of/vs/ ry G. P. HAM E1- Al. 2,255,731

PHOTOGRAPHIC DEVELOPER sept. 9, 1941.`

2 Sheets-Sheet 2 Filed March 15, 1940 u n u {@4' ono/zzo /o anys ll 'iIl ll FIG.4.

I VENTOR. Garne Phi/ip Ham #7nd ,Pober' Bow/ing Barnes ATTORNEY.

Patented Sept. 9, 194i PHOTOGRAPHIC DEVELOPER Garnet Philip Ham,Riverside, and Robert Bowling Barnes, Stamford, Conn., assignors toAmerican Cyanamid Company, New York, N. Y., a corporation of MaineApplication March 15, 1940, serial No. 324,098

(ci. :a-8s) Claims.

This invention relates to improved silver halide photographic developerscapable of withstanding aerial oxidation.

Photographic developers for silver halide material have atendency todeteriorate if exposed vto the air over long periods of time. The effectAis even more pronounced in the strongly alkaline solutions of some highenergy developers.` In addition degradation compounds are formed in thesolutions which materially retard the developing action, and if thedeveloping solution is also exhausted through developing a large area ofsensitive material, the eiect ofsuch silver complex sludges is greatlyexaggerated.

In the past deterioration of alkaline developing solutions has been,partly diminished by the inclusion of sodium or other soluble alkalinemetal sultes in the developing solution. It is thought that the suli'lteacts as an oxidation inhibitor, being more readily oxidized than thedeveloping agents themselves.

While sodium sulte does produce a large measure of inhibition againstaerial oxidation, there are certain classes of medium energy developingsolutions and even those yof low energy type whichy are -by no meansfully protected. Increasing the amount of the inhibitor in suchsolutions generally detracts from the eiiiciency of' the developer dueto the solvent action of the suliite upon the latent image whichobtainsv its best eiliciency when the latent image is such v that afterdevelopment it possesses a density of.

approximately 0.8. Y

According to the presxxt vinvention we have vfound that those developerswhich contain a soluble sulte as oxidation. inhibitors can be furtherfortified, against aerial oxidation by the addition-.of an amidine saltof an amnobenzoic acid inthe developing solution. Organic basescontaining the -C=NH.

NH2 or amidine group suchas benzamidine, acetamidine, guanidine,guanylurea, biguanide and their alkyl, hydroxyalkyl and arylsubstitution products are suiciently basic to enable them to form saltswith such aminobenzoic acids as anthranilic acid, andthe addition ofsuch salts to photographic developingsolutions constitutes the imweprefer to use salts of anthranilic acid .and an an amidine containing aguanyl radical such as guanidine anthranilate, biguanide anthranilateand guanylurea anthranilate.

The secondary inhibitors of the present invention may be added. to anystandard developing provement'oi the present invention. While theinvention broadly includes any amidine salts of formula, the optimumamount varying with different developers. This is an advantage as thephotographic technician may still employ his known solution and byadding the-compounds of the present invention render his developingsolutions more eicient for longer periods of time, thereby eecting greatsavings in cost. 'At the same time the quality of the development, thatis, density, gradation, and contrast val'ues are not diminished. In someinstances the developers containing the inhibitors of the presentinvention, even after long exposure, have actually ,caused an increasein density over that originally obtained from the fresh developer.Furthermore, these secondary inhibitors do not cause any deleteriouselect. on the lm material such as over-softening of the gelatin, nor arethere any difficulties attendant with subsequent fixing or hardeningsuch as reticulation, nor is there any noticeable change in thetransmission .or exibility of the iilm support. Likewise, there is noeilect on the grain size and distribution.

creasingly less aiinity 'for atmospheric oxygen;

or the new compounds .themselves may act as anti-oxidants in thesolution due to their low oxidation potential (approximately 0.4 V-t 25)Perhaps it is neither one nor the other, but a combination of these twofactors, or some entirely dierent phenomenon that accounts for the greatinhibiting eilect of this class of compounds. Whatever the cause ortheoryv of action, we have discovered that the use of such compounds indeveloping solutions enhances not only the keeping qualities, but as ispointed out' above,

in some cases densities are obtained exceeding those of the freshdeveloping solution. Thus poor quality developers, that is, thosedevelopers hitherto unfit for wide usedue to their susceptianyamino-benzoic acid, in a more specific aspect bility'to deteriorationand other drawbacks such as rapid exhaustion, can be made to serveemciently over long periods of time.

'Ihe results obtainable by the present invention are illustrated in thedrawings in which:

Fig. 1 is a series of curves obtained by a ne grain developing solutioncontaining guanidine anthranilate, biguanide anthranilate and guanylurea anthranilate, respectively;

Figs. 2 and 3 are similar sets of curves obtained by DK60 and DK50developing solutions containing guanidine anthranilate; and

Fig. 4 is a series of curves obtained by a D19 developing solutioncontaining guandine anthranilate and guanyl urea anthranilate,respectively.

The invention will be further described in the following examples whichshow the use of secondary inhibitors of the present invention in variousstandard developing solutions. It is not ln- Itended, however, thatthese illustrations should in any way limit the scope of the presentinvention, for as stated above. any standard developing solution may beused. Furthermore, the amount of inhibitor compound to be used may varywithin a wide range depending on the particular solution employed, theextent to which it is subject to oxidation, the alkalinity of thesolution, and the length of exposure time to atmospheric oxidation.

In general we have found that amounts of from 1 to 5 grams per liter ofsolution are effective to give optimum results for most of the standarddevelopers. Larger amounts do not show any increased effect, and in factwe have found that the addition of excessive quantitiesoftheinhibitorhas a retarding action on the developer. In some cases it may be founddesirable to use a combination of inhibitors of the present invention toobtain some special result.

El'ample 1 Four developing solutions were prepared according to thefollowing formula:

The components are mixed in the order given.

`One solution was left as a control, and the other three were treatedwith 1 g. respectively of guanidine anthranilate (GA), biguanideanthranilate (BA) and guanylurea anthranilate (GUA) per 1000 ml. ofdeveloper solution. Portions of all four solutions at room temperaturewere then subjected to oxidation by bubbling air through at the rate of1 bubble per second for a continuous 5-day period.

A photographic wedge with logarithmic steps representing a 50% increasein exposure from step to step, was contact printed onto a series ofportions of 35 mm. supersensitive panchromatic film, using an extremelyaccurately controlled uniform exposure obtained by using as an exposinglight a beamA from a Leitz enlarger with the lens stopped down to itssmallest opening.

A series of strips of film were then developed, one in each of thedeveloping solutions both before and after oxidation, for a. 1li-minuteperiod at 21 using stagnant development in each case. The denstometricvalues of the finished lms Example 2 Two Eastman DK60 solutions wereprepared according to the following formula:

Water milliliters" 500.00 Metol grams-- 1.25 Sodium sulte, des do 15.00Hydroquinone do 1.25 Kodalk do 10.00 Potassium bromide do 0.25

One solution was left as a. control, the other being treated with 5 g.of guanidine anthranilate per 1000 ml. of developer solution. Portionsof both solutions were then subjected to the same oxidation as inExample 1. At the termination of a Z-day, B-day and 4-day periodphotographic wedge strips, prepared as in Example 1, were developed' inhorizontal stagnant manner in each of the solutions for a. rI-minuteperiod at 18. After fixing, the strips were measured on a densitometer,and the results plotted as is shown in Fig. 2.

The control solution after the 2-day oxidation had its density decreasedfrom 1.25 to 0.85, whereas the solution containing the guanidineanthranilate showed a density of 1.33, greater than the density of theunoxidized control.

After three days the control density had dropped to about .58, whereasthe density of the solution fortified with guanidine anthranilate was.95, and after four days of oxidation the control showed no developmentwhile the guanidine anthranilate still had a density of .6.

Example 3 Four Eastman DK50 solutions were prepared according to thefollowing formula:

Water milliliters-- 500.00 Metol grams-- 1.25 Sodium sulte, des do 15.00Hydroquinone do 1.25 Kndalk dO.. 5.00 Potassium bromide do 0.25

One solution was left as a control, the other three being treated with10, 20 and 50 g. of guanidine anthranilate per 1000 m1. of developer.Portions of all four solutions were oxidized as described in Example 1but the rate of air was ncreased to 5 bubbles per second, and oxidationcontinued for six hours.

Photographic wedge strips prepared as in Example 1 were developedstagnantly for a 'Z-minute period at 18 C., nxed, and the densitymeasured and plotted as is shown in Fig. 3.

It is evident from a study of the graph that the solutions containing10, 20 and 50 g. of the :lnhibitor per liter of developing solutionafter being subjected to oxidation still showed densities ofapproximately 1.0, but the control density had dropped from 1.3 to 0.85.However this test indicates that increasing the amount of inhibitor doesnot materially increase the stability, for the densities of thedevelopers containing 10 and 20 g. per liter of solution were the same,and the 50 g. only slightly higher.

Example 4 Three Eastman D19 solutions were prepared according to thefollowing formula: f

One solution was left as a control, the other two being treated with lg. respectively of guanidine anthranilate and guanylurea anthranilate-per 1000 ml. of developer. Portions of all three solutions wereoxidized as in Example 1 continuously for 5 day and 10 day periods..Photographic Wedge strips, prepared as in Example 1, were developedstagnantly for a 5-minute period at 18 C. and then xed with a standardxer. The strips were then measured on a densitometer and thecurvesobtained are shown in Fig. 4.

Example 5 Two 1 liter portions of the developer of Example 1 wereprepared, one being used as a control and the other wastreated with 1gram of acetamidine anthranilate. Both portions of developer weredivided into two parts, one part being blown with air for ve days asdescribed in Example 1. A wedge strip was printed on Eastman panatomicX35 mm. lm as described'in conjunction with the wedge strips onsupersensitive lxn in Example 1. Four identically exposed strips weremade, one strip being developed in the unoxidized control developer,another in the oxidized, and two more in the unoxidized and oxidizeddeveloper with the acetamidine anthra' nilate. The control developerafter five days oxidation showed no development at all, the result beingthe same as that obtained with a fast 1 emulsion in Example 1. In thecase of the oxidized developer to which the acetamidine anthranilate hadbeen added blowing for ve days had v lsome eiect but the developer stilloperated to produce 'a satisfactory development. The inhibiting actionof acetamidine anthranilate, while effective, is not quite as strong asthat of guanidine anthranilate.

1. A silver halide photographic developer containing atleast one silverhalide developing agent, a soluble sulte and an effective amount of anamidine salt of an aminobenzoic acid.

2. A silver halide photographic developing solution containing at leastone silver halide de.

veloping agent, a soluble sulfte and an effective amount of an amidinesalt of an aminobenzoic acid, said amidine salt containing a guanylradical.

3. A metol-hydroquinone photographic developing solution containing asoluble sulte and an effective amount of an amidine salt of anaminobenzoic acid.

4. A metol-hydroquinone photographic developer containing a solublesulte and an eiective amount of an amidine salt of an aminobenzoic acid,said amidine ysalt containing a guanyl radical.

5. A silver halide photographic developing solution containing at leastone silver halide developing agent, a soluble suli'te and an eiectiveamount of an amidine salt of anthranilic acid.

6. A silver halide photographic developing solution containing at leastone silver'halide developing agent, a soluble sulte and an eiectiveamount of an amidine salt of anthranilic acid, said amidine saltcontaining a guanyl radical.

7. A metol-hydroquinone photographic developing solution containing asoluble sulte and an eective amount of an amidine salt of anthranilicacid, said amidine salt containing a guanyl radical.

8. A metol-hydroquinone photographic developing solution containing asoluble sulfite and guanidine anthranilate in eiective amounts.

9. A metol-hydroquinone photographic developing solution containing asoluble'sulfte and -biguanide anthranilatey in effective amounts.

10. A metol-hydroquinone photographic developing solution containing asoluble sulte and guanyl urea anthranilate in effective amounts.

ROBERT BOWUNG BARNES. GARNET PHILIP HAM.

